Robins, Red-winged Blackbirds, and Sandhill Cranes all made their appearance in our area in the last few weeks, right on schedule. Other early spring migrants that have been spotted include grackles, kingfishers, and Red- breasted Mergansers.

By mid-April, phoebes, White-throated Sparrows and Song Sparrows should be arriving. And the month of May will bring a whole host of warblers, vireos, Rose-breasted Grosbeaks, Baltimore Orioles, Ruby-throated Hummingbirds, and many more.

I spotted a pair of Sandhill Cranes in a field between South Boardman and Fife Lake a few days ago. They were happily probing the ground with their sharp beaks, which are designed to penetrate frozen ground. Their diet is varied and includes invertebrates, roots of aquatic plants, rodents, frogs, lizards, snakes, berries, seeds, and cultivated grains.

So what triggers their migration north?

Cranes are opportunistic fliers, relying on thermals and tail winds to carry them along. Thermals are rising columns of warm air, and when southerly winds start to blow in late March and early April, you will see cranes using them on their journey north.

Robins are a bit different in choosing the appropriate weather conditions for their flight. They generally travel north along a geographic line where the average 24-hour temperature is 37 degrees Fahrenheit. This geographic line is called the 37-degree isotherm. As the line moves north, so do the robins. This average temperature provides thawing ground for robins to hunt for their favorite food: earthworms. If the weather returns to winter (and it usually does) the robins will seek out berry bushes that still have fruit. They can also eat small snails, reptiles, and amphibians.

Warblers fuel their migration in large part by hatching caterpillars. Most people know that a butterfly or a moth starts as an egg, hatches out into a caterpillar, pupates into a chrysalis, and then emerges as an adult. Many moth and butterfly eggs synchronize their hatching with the leaf-out period of deciduous trees, so the caterpillars have plenty of fresh green leaves to eat. If warblers arrive a day or two early, before the leaves are out, they will stay near water where abundant aquatic insects are emerging. But most warblers will arrive just as the trees are leafing out, to feast on the plentiful caterpillars that are hatching.

In addition to nectar, hummingbirds need protein in their diet. They get this protein from tiny insects like aphids, picking them off the leaves of plants, and by snapping up tiny gnats out of midair. Some people feed hummingbirds and small flycatchers by setting out chunks of banana and melon in a small mesh bag. The fruit attracts fruit flies, and the hummingbirds dart this way and that, snapping up the bugs that swarm around the fruit.

It’s fun to keep track of the first date you see a certain species of bird, and compare your early dates from year to year. My first dates for last year were as follows: March 18- First Robin; March 19- Woodcock; March 20- Sandhill Cranes; April 20- Golden-winged Warbler and White-throated Sparrow; May 4- Rose-breasted Grosbeak; May 11- Ovenbird, Yellow Warbler, Baltimore Oriole, Great-crested Flycatcher; May 12- Ruby-throated Hummingbird.

The Kalkaska Conservation District can advise you on plantings to attract birds, butterflies, and other wildlife to your property. For more information, call Renee Penny, Conservation Specialist at (231) 258-3307, or email her at renee.penny@macd.org.